Conventionally, in order to observe obstacles in front of, to left and right sides of, and behind a vehicle, radars, such as laser radars or millimeter-wave radars, are used. These millimeter-wave radars include a distance measurement function for measuring the distance from the vehicle to an obstacle by using a millimeter wave having a wavelength of 1 mm to 10 mm, and a very high frequency of 30 GHz to 300 GHz, or a speed measurement function for measuring a speed with respect to an obstacle. Moreover, examples of the intended use of the radars are for Pre-Crash Safety (PCS) or adaptive cruise control (ACC), which is a control system assisting warnings, displays, risk aversions, and the like.
FIG. 4 is a diagram showing an example of a conventional front structure 40 of a vehicle equipped with a millimeter-wave radar. (a) of FIG. 4 shows a bottom view of the front structure 40, and (b) of FIG. 4 shows a front view of the front structure 40.
The front structure 40 of the vehicle includes a front right side millimeter-wave radar 401a, a front left side millimeter-wave radar 401b, a bumper reinforcement 402, a condenser 403, crash boxes 404, and brake ducts 405.
In this front structure 40, for example, an impact energy in the event of collision from the front of the vehicle is dispersed by the bumper reinforcement 402 to front side members (not shown) at the left and the right. The dispersed energy is then efficiently absorbed by the front side members which are highly improved in yield strength by means of high tensile steel plates, or the like. Also, by providing the crash boxes 404 at joints between the bumper reinforcement 402 and the front side members, respectively, a collision energy in the event of a minor collision is absorbed by the crash boxes 404, thereby suppressing the deformation of the body.
The front right side millimeter-wave radar 401a and the front left side millimeter-wave radar 401b shown in FIG. 4 are secured on end portions, of the bumper reinforcement 402, at the left and the right, by using the bracket members 406, respectively.
Also, a radio-wave radar for vehicle is disclosed that realizes cost reduction, while maintaining the radar function, by reducing the number of components as well as improvement of the external design of the vehicle (e. g., see Patent Literature 1).    Patent Literature 1: Japanese Laid-Open Patent Publication No. 11-231041